Category Archives: How-To

How to, maintenance and other technical aspects.

Fabricating your own pinball plastics and lane guides

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As work continues on the restoration of the Bally Mr. & Mrs. Pac Man machine, I have run into a problem.  I got the machine working, but after playing a few games I noticed the ball getting stuck next to the lower left flipper.  The problem is, this game used a piece of plastic as part of the rail guide that had one end chipped off, forming a crevice the ball would constantly get stuck on.  This is not a printed plastic and this game doesn’t have a whole lot of available spare parts for purchase at various places, so my main option is to fabricate my own lane guide…

After a quick trip to the hardware store to pick up the parts, I show off one of the cool tools in my workshop…

After cutting out the plexi piece, let’s see how it looks…

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Work continues on the Bally Mr. & Mrs Pac Man Pinball Game

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In the continued saga of bringing this 1980s game back to life, I begin to go over the electronics and figure out why the game wouldn’t boot up.  Normally you fire up these Bally machines and count the number of times the LED on the MPU board blinks, but in this case, the game didn’t even get far enough to begin to start up the MPU.  Fuse F3 kept blowing and the game wouldn’t power up at all…

An examination of the schematics showed an area on the power rectifier board where it was likely some components were damaged and needed to be replace.  Luckily, these were not very obscure items so I could pick them up easily.

Stay tuned for the next installment where I go into addressing an issue with a broken plastic rail guide that probably can’t easily be replaced, so I have to fabricate my own!

 

EM Tech: Setting credit/extra ball award levels on Gottlieb machines

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Here’s a quick little video on how to change settings on older Gottlieb electro-mechanical pinball games.  If you want to change the threshold at which a credit or extra ball is awarded based on points, there’s a plug in the head of the machine where you move pins to indicate score levels to set awards.

Earthshaker: Working on bad circuit boards

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Let’s take a look inside the backbox of the game and see what we see…

Now that we’ve identified some issues with the aux power board, we have to deal with it, first by removing components…  Oh by the way… I’ve rightfully caught a lot of flack from the folks on rec.games.pinball about my “bridge rectifier removal technique”… Let me elaborate on that… Korn and others are 100% right in that it’s always bad to try and “force” any components from the board, and if solder is not properly melting, it’s best to re-flow new solder onto the old joint to help remove stuck pins.

I would like to say in my defense, this board was really messed up beforehand.  The traces and thru-holes were already damaged on the board, and I had carefully loosened most of the pins of the BR before turning on the camera, so it looks like I’m using more of a “gorilla” technique than in reality.  So that’s not a good example of the best way to remove components, but I knew already I was going to have to rebuild all those traces and I was a tad impatient.  My bad.

Now we begin work on the actual circuit board and show how to identify broken traces and find where they go so we can run jumpers. Looking at the schematics helps us double check everything.

Now putting the finishing touches on the jumpers and adding the bridge rectifiers…

Now comes the moment of truth, putting the repaired aux power board in the machine and turning on the power for the first time:

So far so good for my first major Sys11 repair.  While I have a few Sys11 games, I haven’t had to do a whole lot of repair work on them so this was a learning experience for me too.

Before you turn a new game on: checking coils

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Since we picked up this Williams Earthshaker in such horrible condition and have never seen it powered up, before we even attempt to turn it on, we need to go over some areas of the game to make sure that applying power doesn’t cause more harm.  In this article, I go over one check, which is making sure all the coils/solenoids are in good condition.  A burned-out coil can cause damage in other areas of the machine, or even a fire.

Protecting and sealing pinball backglasses

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Continuing the ongoing saga of restoring a Williams Earthshaker, in this episode, I take a look at the backglass and go over some basic ideas on how to preserve and secure an old backglass from further flaking and damage..

After waiting awhile, let’s take a look…

Ok… we wait awhile and check it, and add some more coats..

So what do you do about clear areas on the backglass? You need to avoid creating any kind of “haze” that obscures score reels or other things that need to be viewed behind the backglass/translight. Here is how we deal with that:

Some additional tips:

  • When you work on the backglass, make sure the humidity and temperature levels are moderate.   It should neither be too dry nor too humid, but err on the dry side where possible.

  • Avoid cleaning either side of the backglass until after it has been treated, especially the screen-printed side.  Even if the screen-side is dirty, it’s best to seal in the dirt, rather than clean it and run the risk of causing the backglass to flake or crack.  However if you want to dust it with something like a Swiffer, you can try to do that, but again, be very careful that the Swiffer doesn’t hook on to any flaking and pull it off.  Ultimately it’s best to seal the screen-side before even trying to wipe down the front – you don’t want to risk getting any moisture on the screen side until it’s sealed.

  • Make your first 2-3 coats relatively thin.  Don’t slather on the Triple Thick unless you do it after several coats have dried and started to seal the backglass well.  There’s a lot of evidence that moisture if subjected to certain types of screens, can cause the backglass to wrinkle and peel off catastrophically.   So take your time and put a few very light coats on at first and see how the backglass reacts.

  • If you may have any loose flakes on the backglass, be very careful with the first few coats of Triple Thick.  Watch your spray angle and spray downward instead of across or you might risk blowing flakes of backglass around.

  • Spray in a well-ventilated area, or immediately leave the area after spraying

  • Avoid subjecting the backglass under any conditions, to freezing temperatures.  This may cause the various materials (containing different amounts of moisture) to expand and contract at different rates and cause cracking and flaking.

Fixing a dead dot matrix display board

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The other day the DMD just went “poof” on one of my machines.  After doing a little research, and checking connections and things, I realized the DMD board died.  In this installment, I walk through the process of rebuilding the power supply-portion of a Bally/Williams WPC DMD board.  In part 1 I describe what I’m doing and introduce you to the tools I’m using.

 

Next up, let’s talk about using a meter to check circuit board traces as we go along..

Desoldering and replacing components.

Now the moment of truth!  One thing I want to add is pay very close attention to each item you are replacing on these boards.  Two diodes, capacitors or transistors may look alike, but have slightly different values or part #s.  The three power transistors and the diodes are not all the same.  You may have to bust out a magnifying glass to note the different in the markings on each part.  This should also be cross-referenced with the schematics and/or parts list from the game manual.